A microphone array, which includes a plurality of microphones, may provide a sound source directivity of a received sound signal by processing received sound signals, to which respective received sounds are converted by the microphones.
For improving an S/N (signal-to-noise) ratio of an output sound signal, a microphone array device processes sound signals from its microphones so as to suppress undesirable noises that are contained in sounds incoming from directions other than a target sound source direction or from a suppression direction.
A known microphone array device includes an estimating unit for estimating a sound signal to be received by a virtual microphone, in a time domain based on sound signals received by a plurality of real microphones, where it is assumed that one or more virtual microphones other than the plurality of real microphones are provided. Thus, an array including a few real microphones is used to provide characteristics equivalent to those of an array of many real microphones.
A known noise eliminating device includes a frequency analyzer for computing a frequency spectrum of an input sound signal, a noise power spectrum estimating unit for estimating a noise component included in the input sound signal, a subtractor for subtracting the noise power spectrum from the input power spectrum, and a frequency synthesizer for recovering a sound signal in a time domain from a phase spectrum from the input sound signal and the power spectrum from the subtractor. The noise power spectrum estimating unit extracts, as a noise power spectrum, a power spectrum of low level powers over respective frequencies during a given period of time, so that the noise power spectrum is estimated without detecting a noise interval.